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SwiftGRB

GRB 050509B Spectra

(BAT)

BAT Spectra

(top)

The BAT spectra shown below were produced by the Swift software task batgrbproduct. Each spectrum was fitted with two models using Xspec: A simple power-law normalized at 50 keV, and an exponential cutoff power-law, also normalized at 50 keV. Each model fit for each interval are shown below, and a table of the fit parameters for each model are shown below each set of plots.

The response matrices for the Pre-Slew and Post-Slew intervals were generated by the Swift software task batgrbproduct, which uses the Swift software task batdrmgen. For any interval where the spacecraft was slewing, the response matrix was generated by first generating a response matrix for every 5 second interval during the slew. Then the 5 second response matrices were averaged with weighting based on count rate.

See this paper for details.


Pre-Slew Spectrum

This BAT spectrum is from the time interval (MET [s]: 137304018.744 - 137304018.792) before the spacecraft slewed to the burst position.

BAT Pre-Slew Spectrum: Power-law Fit

BAT Pre-Slew Spectrum: Cut-off Power-law Fit

Best Fit Model: Power-law

Power-law Model Parameters

NameValue (Low : High)
Power-law Index1.678 (1.553 : 1.803)
--
Normalization0.01518
Flux 15-25 keV*2.292e-08 (1.77e-08 : 2.988e-08)
Flux 25-50 keV*3.777e-08 (3.213e-08 : 4.486e-08)
Flux 50-100 keV*4.72e-08 (3.758e-08 : 5.658e-08)
Flux 100-150 keV*3.29e-08 (2.353e-08 : 4.452e-08)
Flux 15-150 keV*1.408e-07 (1.171e-07 : 1.671e-07)
Chi-Squared51.74
Degrees of Freedom56
* All fluxes have units of ergs cm-2 s-1

Power-law+Cutoff Model Parameters

NameValue (Low : High)
Power-law Index-1.056 (-1.734 : -0.378)
Cutoff (keV)61.67 (55.84 : 67.5)
Normalization0.2904
Flux 15-25 keV*1.3e-08 (4.332e-09 : 1.581e-08)
Flux 25-50 keV*4.832e-08 (2.043e-08 : 5.05e-08)
Flux 50-100 keV*6.556e-08 (2.069e-08 : 7.196e-08)
Flux 100-150 keV*1.718e-08 (2.308e-09 : 2.511e-08)
Flux 15-150 keV*1.441e-07 (5.006e-08 : 1.609e-07)
Chi-Squared45.74
Degrees of Freedom55
* All fluxes have units of ergs cm-2 s-1

Total BAT Spectrum

This is the total spectrum of all of the above intervals (MET [s]: 137304018.744 - 137304018.792).

BAT Total Spectrum: Power-law Fit

BAT Total Spectrum: Cut-off Power-law Fit

Best Fit Model: Power-law

Power-law Model Parameters

NameValue (Low : High)
Power-law Index1.678 (1.553 : 1.803)
--
Normalization0.01518
Flux 15-25 keV*2.292e-08 (1.703e-08 : 2.983e-08)
Flux 25-50 keV*3.777e-08 (3.091e-08 : 4.446e-08)
Flux 50-100 keV*4.72e-08 (3.773e-08 : 5.679e-08)
Flux 100-150 keV*3.29e-08 (2.322e-08 : 4.549e-08)
Flux 15-150 keV*1.408e-07 (1.158e-07 : 1.689e-07)
Chi-Squared51.74
Degrees of Freedom56
* All fluxes have units of ergs cm-2 s-1

Power-law+Cutoff Model Parameters

NameValue (Low : High)
Power-law Index-1.056 (-1.734 : -0.378)
Cutoff (keV)61.67 (55.84 : 67.5)
Normalization0.2904
Flux 15-25 keV*1.3e-08 (4.468e-09 : 1.615e-08)
Flux 25-50 keV*4.832e-08 (1.983e-08 : 5.07e-08)
Flux 50-100 keV*6.556e-08 (1.941e-08 : 7.233e-08)
Flux 100-150 keV*1.718e-08 (2.658e-09 : 2.52e-08)
Flux 15-150 keV*1.441e-07 (5.438e-08 : 1.553e-07)
Chi-Squared45.74
Degrees of Freedom55
* All fluxes have units of ergs cm-2 s-1

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